Electronic systems and circuits have made a significant contribution towards the advancement of modern society and are utilized in a number of applications to achieve advantageous results. Numerous electronic technologies such as digital computers, calculators, audio devices, video equipment, and telephone systems facilitate increased productivity and cost reduction in analyzing and communicating data, ideas and trends in most areas of business, science, education and entertainment. Electronic systems designed to produce these results usually involve interfacing with a user and the interfacing often involves presenting graphical representation of images. Displaying graphics images usually requires intensive data processing which traditionally takes considerable time to process and often consumes significant power.
Computer graphics systems typically utilize a sequential stage or “pipeline” type process to map a three dimensional scene in the world coordinate system to a two dimensional projection (e.g., on a display screen). In most computer graphic systems an image is represented as a raster (an array) of logical picture elements (pixels). Pipelines typically assign parameter values to each pixel and the parameter values determine the nature of the projection on the display screen. The parameter values are digital values corresponding to certain attributes of the image (e.g. color, depth, etc.) measured over a small area of the image represented by a pixel. Typically each graphical image is represented by thousands of combined pixels. Providing information for each pixel is very data intensive and consumes a significant amount of processing resources.
There are a number of stages or processes included in a typical graphics pipeline. Various manipulations of pixel data are implemented at each stage in the pipeline. These manipulations often involve numerous computational processes that take a relatively long time to complete. In addition, the processing consumes significant power and can be a significant drain on limited power supplies, such as a battery. One process performed in a typical graphics pipeline is to eliminate pixel values that are occluded, such as values associated with “hidden” surfaces. The occlusion determining process typically occurs near or at the end of a graphics pipeline after a number of processing operations have been performed to establish a variety of pixel values. These processes are often performed even on pixel values that are eventually discarded at the end of the graphics pipeline.
The rate at which images are rendered in typical graphics systems is often critical to proper presentation of the information. Slow rendering rates often result in undesirable choppy or “jerky” presentations which usually results in a user experience that is non-immersive and unpleasant. The rate at which graphics systems can render images is often limited by the rate at which the processing devices can process the graphics information. However, user's tend to have ever increasing demands for ever more spectacular and clearer images with better resolutions. Achieving better resolution often involves more graphic information processing and advanced applications. As more information associated with sophisticated applications and complex image rending is fed into traditional graphics pipelines the time required to process all the information increases since the graphics processing capabilities of the graphics systems typically have an upper limit. In addition, accessing the increased amounts of information also increases the time involved in retrieving the information from various memories. The increases in time to perform processing and information accesses typically slows the rendering rate and adversely impacts the graphics presentation.